First of all this forum has a rule for one thread per game, this applies to homebrew as well and this app already has an existing thread in here.

That error means file was not found, which assuming you have all the files I can only guess means you're trying to run homebrew from some random folder - which is NOT supported.
To run homebrew games/apps properly you have to copy them inside memstick/PSP/GAME/ folder, the same one where all homebrew from ppsspp built-in homebrew store are installed. It's also recommended to use latest ppsspp builds as there were some changes affecting homebrew which were merged after last big version was released.

It's generally NOT recommended to run emulators inside emulators through, expect other issues. Most PSP homebrew emulators(as well as some commercial ones) draws some graphics(especially menus) in weird manual ways that will never be supported in hardware rendering, so if you want to see all their graphics without glitches you will need to activate software rendering in graphics settings before running it.(not available on mobiles, outside of manual ini file editing since it's too slow to be usable there anyway)